Window coverings can be configured so that a material is moveable to partially or fully cover a window. Examples of window coverings can be appreciated from U.S. Pat. Nos. 7,984,745, 7,331,370, 7,311,133, 7,228,797, 7,108,038, 7,025,107, 7,021,360, 6,761,203, 6,725,897, 6,644,373, 6,644,372, 6,601,635, 6,571,853, 6,289,965, 6,234,236, 6,283,192, 6,129,131, 6,024,154, 5,706,876, 5,482,100, 3,129,750, 2,420.301, and 13,251 and U.S. Pat. App. Pub. Nos. 2012/0111509, 2010/0243177, 2007/0056692, and 2007/0051477.
Spring motors that may be employed in window coverings can often include spring elements that can add substantial cost to the spring motor unit. For instance, the spring member of the spring motor unit may require use of a substantial transmission system as disclosed in U.S. Pat. No. 6,283,192 or may require use of a type of spring member that has a special construction that can be expensive to help facilitate the support of the variable load of the window covering material as that material is raised or lowered.